The present invention relates to the field of protective equipment, specifically orthosis and/or apparel that serves as a body guard or body protector.
More particularly, it relates to a dynamic joint motion control system which is typically worn while participating in a sport or active recreational activity such as skiing or snowboarding. The present invention also relates to a system of dynamically fitting and anchoring body protection devices by using motion at a body joint to actuate a closure mechanism that actively closes upon the body anatomy surrounding the joint.
It should be understood that the present invention relates generally to kinematic control of body joints or body parts, and most importantly, to the prevention of terminal extension or flexion at a body joint. The present invention, as will be discussed in detail below, is capable of restraining the relative motion of any body part of an individual but has particular application in preventing terminal wrist dorsiflexion, also referred to as terminal wrist extension. Therefore, any reference to a body joint or body part is understood to encompass the wrist and any reference to the wrist alone is intended to include applicability to any body part. For ease of discussion and illustration, discussion of the prior art and the present invention is directed to the human wrist, by way of example and is not intended to limit the scope of discussion to the human wrist.
Excessive motion of body joints or excessive impact loads to the body can cause serious injury or death. There is a need to protect soldiers, athletes, industrial workers and economic animals from over-stressing parts of their anatomy when linear and/or rotational joint motion (displacement, velocity, acceleration) exceeds critical levels or when the body is struck by impact blows.
There are several joints that need this kind of protection including (but not limited to) the knee, ankle, wrist, thumb, fingers, shoulder, ankle, neck, and elbow. Excessive joint motion can result in fractures, sprains, and other problems. In order to prevent such injuries, it is desirable to dynamically control rotational and/or translational displacement and velocity of a body part.
For example, in sports such as snowboarding and in-line skating as well as in the elderly population, wrist injuries are common. The Centers for Disease Control and Prevention (CDC) have reported significant wrist fracture data in 3 segments of the population: in-line skaters, snowboarders, and the elderly, particularly osteoporotic women (Table 1). See Centers for Disease Control and Prevention. Incidence and Costs to Medicare of Fractures Among Medicare Beneficiaries Aged greater than or equal to 65 Years—United States, July 1991-June 1992. Morbidity and Mortality Weekly Report. 1996; 45(41): 877-883.
The 1996 National Electronic Injury Surveillance System (NEISS) data for in-line skating estimates almost 300,000 injuries per year, of which as high as 56% have been reported as wrist injuries. See National Electronic Injury Surveillance System, In-Line Skating Safety Statistics, 1996, accessed at http://www.iisa.org/resources/safety.htm#1996%20injuries on Jun. 27, 2002 and Malanga, G., Stuart, M., 1995. In-line skating injuries. Mayo Clinic Proceedings 70, 752-754.
The incidence of wrist fracture in snowboarding has been reported as high as 1.02 fractures per 1000 snowboarder days. Greenwald R M, Senner V, Swanson S C: Biomechanics of Carving Skis, Sportmedizin und Sporttraumatologie, 49(1): 40-44, 2001. Wrist injuries as a percentage of total snowboarding injuries have been reported between 18.7% and 21.6%. Sasaki, K., Takagi, M., Kiyoshige, Y., Ogino, T., 1999. Snowboarder's wrist: its severity compared with alpine skiing. The Journal of Trauma: Injury, Infection, and Critical Care 46, 1059-1061 and ldzikowski, J., Janes, P., Abbot, P., 2000. Upper extremity snowboarding injuries: ten-year results from the Colorado Snowboard Injury Survey. The American Journal of Sports Medicine 28, 825-832.
Of first-time snowboarders, 53% of injuries are upper extremity injuries. See O'Neill, D., McGlone, M., 1999. Injury risk in first-time snowboarders versus first-time skiers. The American Journal of Sports Medicine 27, 94-97. The CDC reports that wrist fracture is the second most-common fracture among the elderly, with an incidence of 37.8 per 10,000 population. This cost to Medicare is projected at $226 million per year in 1996 dollars. Additionally, NIH reports that over 250,000 wrist fractures annually are caused by osteoporosis. See National Institute of Arthritis and Musculoskeletal and Skin Diseases, Osteoporosis: Progress and Promise. Health Topics, August 2000, accessed at http://www.niams.nih.gov/hi/topics/osteoporosis/opbkgr.htm on Jun. 27, 2002.
TABLE 1Incidence and cost of wrist fractures in the United StatesAssociatedIncidence/yearIncidence/1000Medical CostsWrist Fx(000's)exposures($M's)In-line skating1680.27 $18Snowboarding341.02 $4Falls in the2500.38$226elderly
See also US Consumer Product Safety Commission, CPSC Projects Sharp Rise in In-Line Skating Injuries, NEWS from CPSC, accessed at http://www.cpsc.gov/CPSCPUB/PREREL/PRHTML95/95135.html on Jul. 22, 2002. If the wrist is prevented from reaching terminal extension, it is possible to prevent fracture of the wrist bones. In prior art, conventional wrist guards are typically constructed from fabric with rigid aluminum or rigid plastic plates or splints crossing the wrist joint on either the dorsal or volar surface of the hand as a protection mechanism against abrasions and/or carpal fractures, including the wrist. Prior art guards limit normal range of motion at the wrist as well as increasing the torque required to achieve terminal wrist extension during an impact event. Biomechanical studies of wrist guard efficacy using matched pairs of cadavers showed that wrist guards increased the force to wrist fracture and absorbed a small percentage of the impact energy following a dynamic impact. See Lewis, L., West, O., Standeven, J., Jarvis, H., 1997. Do wrist guards protect against fractures? Annals of Emergency Medicine 29, 766-769.
Wrist guards were also shown to act in a load-sharing capability by reducing bone strain in the dorsal distal radius during both quasi-static and dynamic loading. See Moore, D. C., Staebler, M. P., Crisco, J. J., Greenwald, R. M., Akelman, E., Weiss, A 2000. Wrist guards reduce impact-generated bone strain in the distal radius. In Transactions of the 46th meeting of the Orthopaedic Research Society. Orthopaedic Research Society, Rosemont and Staebler, M., Moore, D., Akelman, E., Weiss, A., Fadale, P., Crisco, J., 1999. The effect of wrist guards on bone strain in the distal forearm. The American Journal of Sports Medicine 27, 500-506. Wrist guards also offer the possibility of reducing the friction between the hand and the impact surface. This is particularly important in in-line skating, where the impact surface is often concrete. Clinically, wrist guards limit the incidence and severity of wrist injury. See Schieber, R., Branche-Dorsey, C., Ryan, G., Rutherford, G., Stevens, J., O'Neill, J., 1996. Risk factors for injuries from in-line skating and the effectiveness of safety gear. The New England Journal of Medicine 335, 1630-1635 and Orenstein, J., 1996. Injuries and small-wheel skates. Annals of Emergency Medicine 27, 204-209.
While, force to fracture increased by approximately 50% with wrist guard use, conventional wrist guards did not prevent terminal wrist extension. For relatively high energy impacts, there was no decrease in loading rate near terminal extension with or without a wrist guard, indicating that the effectiveness of the wrist guard is overwhelmed at higher loading rates. See Greenwald R M, Janes P S, Swanson S C, MacDonald T R: Dynamic Impact Response of Human Cadaver Forearms Using a Wrist Brace, American Journal of Sports Medicine. 26(6):1-6, 1998.
Commercially available wrist guards reduce wrist injury incidence and severity, but they suffer from a lack of use in the population most at risk for wrist injuries. Only 2-7% of snowboarders used wrist splints over a eight year study period. See ldzikowski, J., Janes, P., Abbot, P., 2000. Upper extremity snowboarding injuries: ten-year results from the Colorado Snowboard Injury Survey. The American Journal of Sports Medicine 28, 825-832. The primary reason appears to be that the available guards restrict normal range of motion, and are too bulky for most users. In general, epidemiological and biomechanical studies support the conclusion that the use of wrist protection for in-line skating and snowboarding significantly reduces the incidence and severity of wrist fractures. The problem is that very few people actually wear the protective devices because they limit normal range of motion and are generally bulky and unappealing.
In view of the foregoing, there is a demand for a joint motion control system which is low profile, light weight, non-bulky, and non-restrictive to normal range of motion, yet still prevents terminal wrist extension and increases the force to fracture.
The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior designs of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.